Randomizer::pickArrayKeys() has intransparent external behavior

Description

The following code:

<?php

$r1 = new Random\Randomizer(new Random\Engine\Xoshiro256StarStar(1));
$r2 = new Random\Randomizer(new Random\Engine\Xoshiro256StarStar(1));

$a = [ 'a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5, 'f' => 6, ];
unset($a['b']);

$b = [ 'a' => 1, 'c' => 3, 'd' => 4, 'e' => 5, 'f' => 6, ];

var_dump($a === $b); // bool(true)

var_dump(
	$r1->pickArrayKeys($a, 1), // [ 0 => 'e' ]
	$r2->pickArrayKeys($b, 1), // [ 0 => 'd' ]
);

Resulted in this output:

bool(true)
array(1) {
  [0]=>
  string(1) "e"
}
array(1) {
  [0]=>
  string(1) "d"
}

But I expected this output instead:

The same key selected, because the arrays are identical.

PHP Version

Current git master

Operating System

No response

Start with the issue's reproducible example and the PHP documentation for Randomizer::pickArrayKeys(). Determine whether the differing selections for arrays with identical key-value pairs are expected, then clarify the documented behavior and expected result; no specific file or test is named in the issue.